Try to make Docker's crazy COPY happy

containers/python-3/.devcontainer/Dockerfile

@@ -8,9 +8,11 @@ FROM python:3
 # Avoid warnings by switching to noninteractive
 ENV DEBIAN_FRONTEND=noninteractive
 
-# Copy requirements.txt (if found) to a temp locaition so we can install it. Also
-# copy "noop.txt" so the COPY instruction does not fail if no requirements.txt exists.
-COPY requirements.txt .devcontainer/noop.txt /tmp/pip-tmp/
+# Copy requirements.txt (if found) to a temp location so we can install it. The `*`
+# is required so COPY doesn't think that part of the command should fail is nothing is
+# found. Also copy "noop.txt" so the COPY instruction copies _something_ to guarantee
+# success somehow.
+COPY *requirements.txt .devcontainer/noop.txt /tmp/pip-tmp/
 
 # Configure apt and install packages
 RUN apt-get update \